Axial flow combines are combines in which a power-driven rotor is mounted inside a stationary cylindrical threshing cage to thresh and separate the grain, and the material to be separated moves along the axis of the rotor. In such a combine, which has been available for a number of years, the grain is threshed several times repeatedly, but gently, as it spirals around the single large diameter rotor and passes through the threshing cage. A simple system of employing a rotor and a threshing cage incorporating concaves, separating grates and centrifugal force acts to separate the grain and material other than grain, and delivers the grain to the cleaning unit. The rotor threshes and acts to separate the grain from the material other than grain. Essentially, most material other than grain stays within the threshing cage and is directed out the rear end.
While the rotor and threshing cage act to separate a substantial portion of the grain from the material other than grain, some of the chaff or straw is directed out through openings in the cage along with the grain and a further separating action is required. Further separation is normally achieved by forcing a stream of air upwardly through the sieves located below the threshing cage and above the sieve so that the lighter material being expelled from the threshing cage is floated on top of the sieve and is directed out through the end of the combine by the air flow. The heavier seeds or grain tend to move to the sieve and fall through the sieve into a collector. It is clear from the above that an efficient flow of air is necessary to provide a proper cleaning action for threshed grain.
In existing cleaning systems found in axial flow combines, the cleaning function is adversely affected by the rotor air blowing down upon the cleaning system. That is to say that the centrifugal action of the rotor acts to direct turbulent air toward the cleaning and separating system which tends to agitate the material and thus possibly making some of the grain airborne, and subject to being wasted by discharging out the trailing end of the combine.
In the typical prior art combine, air is normally directed from a position below the threshing cage against the material other than grain and grain that is moving outwardly from the threshing cage. The lighter-weight material, other than grain, such as, chaff and straw, is carried along by the air flow and is directed out through the end of the combine, along with the residue that is located within the threshing cage. The residue within the cage is moved into engagement with beaters, or the like, and deposited on the ground at the trailing end of the combine. However, it can be appreciated that in a situation where turbulent air is directed outwardly by the centrifugal forces generated by the rotor into contact with the air being directed by the fan located adjacent the threshing cage surface, this mixture of air flows could adversely affect the flow of the grain down into the cleaning sieves and the grain collecting area.
In accordance with the present invention, there are provided a pair of fans located adjacent the beater disposed at the end of the threshing cage, which fans draw air into an inlet opening in a housing in which the fan is located. With this novel arrangement, a relatively strong current of air is moved along the outer surface of the threshing cage toward the end of the threshing cage which acts to offset the adverse effect of the turbulent air being expelled from the threshing gage. This increases the efficiency of the cleaning system by directing an increased percentage of the material other than grain out of the grain pan and sieve area.
It is noted that the ends of the discharge beater, which is located at the end of the threshing cage, does not do any significant propelling of the rotor discharge out the rear thereof, and thus locating fans adjacent the end of the beater does not significantly impact on the discharge of the material other than grain out the rear of the threshing cage.
In summation, the advantages of locating the fans adjacent the end of the threshing cage to increase the efficiency of the cleaning action are numerous and they include (1) eliminating the adverse effects of the rotor air on the cleaning system, (2) act to eliminate more of the material other than grain from the cleaning system, (3) reduce cleaning system losses, (4) improve the airflow through and above the cleaning system, (5) improve the spreading of the material other than grain, (6) reduce the cleaning system air turbulence by creating a smooth upper surface for air to flow along, and (7) the sieves for separating the grain from the chaff stay cleaner and work better.